1. Field:
This invention relates generally to intravascular catheter systems for introducing fluids, medications, and the like into a patient during medical and surgical procedures and for the clinical monitoring of blood and other parameters of the patient and more particularly to a fluid flow regulating and control unit adapted to regulate the flow of fluid in such system for reliable operation of the in-dwelling catheter in such intravascular catheter systems.
2. State of the Art:
It is well known that for the reliable operation of intravascular catheter systems it is necessary to continuously flush the in-dwelling catheter to maintain the end thereof, disposed in the patient, in an open condition.
Due to the importance of these systems in modern day medical and surgical treatment and procedures, various prior art apparatus has been developed. More recently, improved fluid flow control devices have been developed for use in such intravascular catheter systems as is shown in U.S. Pat. Nos. 3,675,891 and 4,192,303.
Each of U.S. Pat. Nos. 3,675,891 and 4,192,303 describes in detail the nature of intravascular catheter systems, the problems surrounding their operation, the existing prior art and the nature of the improvement set forth respectively in these patents. Accordingly the information disclosed in these patents is incorporated by reference. Broadly each of these patents describes a device for controlling the flow of fluid in the intravascular catheter system so as to provide two basic modes of flow, the first at a continuous relatively low rate and the second an intermittent manually controlled larger flow of fluid to rapidly flush the catheter in the intravascular catheter system from time to time to meet and overcome the problems of maintaining the in-dwelling catheter of these systems open for the reasons as set forth in these patents.
In U.S. Pat. No. 4,192,303 the control device disclosed is connected to the in-dwelling catheter in the intravascular catheter system there shown, to provide continuous flow of fluid to the catheter. Thus, the device includes an inlet and an outlet and a first fluid flow passage connecting the inlet to the outlet to pass fluid through the flow regulating and control device. At least a part of the first fluid flow passage comprises a section of flexible conduit and includes, a valve control means operatively associated with the section of flexible conduit so that when the flexible conduit is manually squeezed the valve control means therein is moved to an open position to permit a relatively large flow of fluid to pass through the first fluid flow passage for the required flushing mode for the in-dwelling catheter of the intravascular catheter system. The valve means will move to its normally closed position when the flexible conduit is released. A second passage is provided having a flow restriction means therein which is disposed relative to the valve control means so that when the valve control means is in the closed position, a predetermined continuous flow of the fluid being controlled is delivered to the outlet, thus bypassing the valve control means to provide the relatively low flow rate of the dual mode operation above described.
One of the problems of the flow regulating and control device disclosed in U.S. Pat. No. 4,192,303 is the fact that the section of flexible conduit is part of the exterior surface of the device and is manipulated by direct manual squeezing, thus presenting the possibility that the flexible section may be damaged inadvertently or otherwise which in the case of many patients who must undergo these required medical and surgical procedures may be subjected to life threatening conditions such as blood loss or failure to receive medication or needed fluids such as in the case of new born infants or the physically handicapped.
The present invention provides another improved flow regulating control unit which is adapted to meet and overcome the same problem overcome by the prior art U.S. Pat. Nos. 3,675,891 and 4,192,303 in which either the dual mode type operation may be utilized or wherein the flow of fluid to the catheter in the intravascular catheter system can be regulated from a predetermined minimum flow to the maximum flow capacity of the flow passage for the fluid being controlled by the flow regulating and control unit. The flow regulating and control unit in accordance with the present invention is characterized by the fact that the fluid flow passage between the inlet and the outlet includes a flexible conduit section which is protected within an operating chamber in the flow regulating and control unit. The fluid flow passage is provided with a continuously open connecting port so that the section of flexible conduit can coact with a restricting device for limiting the flow of fluid through the fluid flow passage. Thus, when axial forces are exerted against one end of the section of flexible conduit a predetermined flow of fluid can be bypassed about the flow restrictor and passed with the metered fluid through the continuously open connecting port to the outlet of the flow regulating and control unit.